Zirconia-based materials have been used to prepare various ceramic materials. Compared to other ceramic materials, zirconia-based ceramics can have improved mechanical strength associated with a phase transformation mechanism that can be triggered when a crack propagates into the ceramic material. More specifically, tetragonal phase zirconia can be transformed to monoclinic phase zirconia under such conditions. The formation of the monoclinic phase tends to arrest the progression of the crack throughout the ceramic material.
Zirconia-based materials have been added to an organic matrix such as a polymeric material to increase the index of refraction or x-ray opacity of the organic matrix. The extent to which the x-ray opacity and/or refractive index of the organic matrix can be increased is dependent on the percent loading of zirconia-based materials in the organic matrix and on characteristics of the zirconia-based materials such as the amount of crystalline material, the crystalline structure, and the average particle size.